Study on acid resistance and high temperature resistance of composite geopolymer-stabilized lead–zinc tailing

Abstract

Geopolymer is regarded as a potential environmentally friendly substitute for ordinary Portland cement, applicable in construction materials. A cementitious material based on coal gangue and blast furnace slag was employed for the solidification/stabilization of heavy metals from lead-zinc tailings, while multi-walled carbon nanotubes were incorporated to enhance the strength of the solidified matrices. The durability of the solidified bodies was assessed against heating at various temperatures (300 °C, 500 °C, 700 °C, 900 °C, and 1100 °C) and exposure to an acid rain simulation solution with varying pH levels (3, 4, and 5). When subjected to heating and immersion in the erosion solution, the inclusion of lead–zinc tailings led to an augmentation in shrinkage, mass loss, strength reduction, and the leaching of heavy metals from the specimens. X-ray diffraction analysis was performed to characterize the phase transformations in the exposed specimens. The compressive strength of the solidified bodies containing 70 wt% lead–zinc tailings decreased significantly under severe conditions. The leaching test results revealed that the leaching concentrations of these specimens remained well below the standard limits. This suggests that the solidified bodies, which were enhanced with multi-walled carbon nanotubes, exhibited good stability.